package com.hit.basmath.learn.others;

/**
 * 463. Island Perimeter
 * <p>
 * You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water.
 * <p>
 * Grid cells are connected horizontally/vertically (not diagonally). The grid is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).
 * <p>
 * The island doesn't have "lakes" (water inside that isn't connected to the water around the island). One cell is a square with side length 1. The grid is rectangular, width and height don't exceed 100. Determine the perimeter of the island.
 * <p>
 * Example:
 * <p>
 * Input:
 * [[0,1,0,0],
 * [1,1,1,0],
 * [0,1,0,0],
 * [1,1,0,0]]
 * <p>
 * Output: 16
 */
public class _463 {
    public int islandPerimeter(int[][] grid) {
        if (grid == null || grid.length == 0 || grid[0].length == 0) return 0;
        int result = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if (grid[i][j] == 1) {
                    result += 4;
                    if (i > 0 && grid[i - 1][j] == 1) result -= 2;
                    if (j > 0 && grid[i][j - 1] == 1) result -= 2;
                }
            }
        }
        return result;
    }
}
